Method and electrolyser for disinfectant production

ABSTRACT

Exemplary electrolytic methods are disclosed relating to preparation of useful products, e.g., disinfectants, from aqueous solutions of electrolytes. Disinfectant production with a capacity of a single electrolyzer may amount to 1200 liters per hour and up to 600 grams of active chlorine per hour by utilizing 3-7 gram sodium chloride (NaCl) for the production of 1 gram of active chlorine on the basis of a reliable and safe hydraulic structure. A fresh water supply may initially be directed into an internal tubular cathode chamber for cathode cooling purposes, before the participation in final disinfectant production process. A coolable cathode may increase the hold-up time of the electrolyte in the electrode chamber without application of circulation circuits, improving significantly the efficiency of sodium chloride utilization. The simplicity of the method makes it possible to increase both the productivity of a single electrolyzer and the efficiency of the process.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. Ser. No. 13/008,742filed on Jan. 18, 2011, which claims priority to Estonian PatentApplication No. P201000069, filed on Sep. 9, 2009, which applicationsare incorporated herein by reference in their entirety.

TECHNICAL FIELD

The disclosure relates generally to the field of chemical engineeringand is used for acquiring production, by using the method ofelectrolysis, on an aqueous solution of electrolyte of variousconcentrations, which can be applied to produce disinfectants such asthat used in the field of health care, biology and ecology. Morespecifically, the disclosure deals with electro-chemical technology forproducing fresh-water based disinfecting solutions by usingdiaphragm-electrolysers.

PRIOR ART

A number of methods are known for producing disinfecting solutions fromanodic produce of an aqueous solution of sodium chloride (NaCl),combined with using cathodic produce of electrolysis for increasing thepH of disinfecting solution or without.

Patents/Applications RU2079575, RU2297980, WO2004/031077 andUS2004/0060815 describe methods, whereby electrolyte with equivalentconcentration—approximately 10 g/l—is simultaneously channelled intoanode and cathode chambers. The anolyte, obtained as the electrolyser'soutput, is a ready to use as disinfecting solution, whereas the pH ofthe anolyte can be adjusted to a certain extent by changing the ratio ofanolyte and catholyte quantities.

According to the inventor, however, these methods are insufficient asthe consequence of low efficiency of salt for obtaining disinfectant, asin the case of a number of technologies, high mineralisation ofdisinfectant will be accompanied by critical accumulation of chloridesin agricultural soil, water circulation pipes of cooling systems, etc.In the case of some other technologies, wherein large quantities ofdisinfecting solutions are used (200 cubic meters, in average), forexample, municipal water and waste water treatment facilities, highdemand for sodium chloride (more than 2 tons per day) will decrease theinterest in implementing these methods. Decreasing the mineralization ofdisinfecting substance by increasing the number of electrolysersproportionally will increase the cost of the method and complicate theexploitation of equipment. Total consumption of sodium chloride per 1gram of active chlorine will be above 12 grams in these methods.

Another material disadvantage of known methods is the need for rationaluse of catholyte, requiring 5-50% water and salt, and which is oftendischarged—without any effect—into waste water disposal systems.

A method, described in patents RU2088539 and RU2208589 is also known,involving discharging electrolyte with sodium chloride concentration ofapproximately 10 g/l, in succession, first into a cathode chamber andthen from the cathode chamber to the anode chamber. In theelectrolyser's output, the anolyte will be a ready-made disinfectantwith the approximate pH level of 9.0. The pH level of the anolyte can bediminished, if applicable, by discharging some of the catholyte forutilisation before being channelled to the anode chamber. Thedisadvantage of the method described is low efficiency of using sodiumchloride—more than 8 grams per 1 gram of active chlorine.

Another method is described in patents RU2148027 and WO02/085795,involving channelling electrolyte with the approximate concentration of2.5 g/l into the anode chamber, while concentrated electrolyte with theconcentration of 100-300 g/l will enter the cathode chamber from acirculation circuit. The anolyte in electrolyser's output is aready-made disinfectant. Approximately 7 grams of sodium chloride willbe used per 1 gram of active chlorine. The disadvantage of the method,however, is to use circulation of the cathode side for cooling andtransfer of electrolyte, which shall further increase the number ofnarrow passages, which will be covered by cathode sediments.

Methods for acquiring disinfecting solution, described in patentapplication WO2006/098660 are also known, involving channellingelectrolyte at the concentration of up to 2 g/l and 1 g/l, respectively,for single and multiple flow, into the anode chamber, in quantitiesequal to disinfectant acquired, not considering the amount of catholyte,required to adjust pH level. Electrolyte from the circulation circuit,which will be mostly filled from electrolyte, out-flowing from the anodechamber, will be discharged into the cathode chamber; the electrolytewill be infiltrated into the circulation circuit through the diaphragm,as the result of difference in pressure, generated in the anode andcathode chambers. Anolyte, obtained from the output of the electrolyserof the latter, is a product ready for use. The efficiency of the methodis approximately 5.0 grams of sodium chloride per 1 gram of activechlorine, but the implementation of the method is aggravated by the needto employ a pressure regulation device and a circulation circuit in theanode channel.

A method for acquiring aqueous solutions of anode oxidation of chloridesolution is also described in patent RU2088693; the method is used forwater cleaning and disinfecting processes, involving channellingelectrolyte—concentrated (up to 300 g/l) sodium chloride solution—intothe anode chamber from the circulation circuit, and fresh water basedelectrolyte into the cathode chamber from the circuit on the cathode'sside. Gaseous anode product, mostly consisting of chlorine, will bedischarged from electrolyser, where it can be mixed with a part of thecatholyte and dissolved to the required concentration in fresh water.The method is characterised by high efficiency (salt requirementapproximately 3 g per gram), but the disadvantages should be alsopointed out—complicated circulation circuits and pressure regulatingdevices, but also enhanced requirements to sealing of joints andchemical resistance of materials, being in contact with the gaseouschlorine.

Patent RU2322397 describes a method for acquiring aqueous solutions ofoxidants, where, as it was the case of the method described earlier,concentrated electrolyte will be processed in the anode chamber. Mostlygaseous chlorine is produced, as the consequence, and fresh water ischarged into the cathode chamber, which will be discharged, once treatedin the cathode chamber, from the electrolyser to be mixed with gaseouschlorine. The presence of highly concentrated gaseous chlorine willrestrict the number of possible spheres for safe use of the equipment.

As this disclosure expects the widest implementation of disinfectantsdeveloped to take place at the sites where the disinfectants are usedmost widely (institutions of treatment and preventive care,establishments producing meat, milk, feedingstuffs and other products,farms, swimming pools, water treatment facilities, etc.), the method forobtaining disinfectants, published in patent application WO2006/098660(example 2, FIG. 2), has been chosen for obtaining disinfectants.

In the method described in the prototype, aqueous solution of sodiumchloride with the concentration of 0.2-2.0 g/l is flowing through theanode chamber, having the active chlorine concentration of a workingsolution in the anode chamber and the electrolyser output. Electrolyte,infiltrated into the cathode chamber from the anode chamber, through thediaphragm, flows through the cathode chamber. Important commoncharacteristics of the prototype and the method, given in the patentapplication, is slow renewal of electrolyte in the cathode chamber andusing fresh water as the starting electrolyte in the cathode chamber.

The main disadvantage of the prototype method is the need to maintain apressure high enough in the anode chamber to ensure sufficient flow ofelectrolytes into the cathode chamber, above all, considering the factthat cathode sediments are created at the anode side of the diaphragm.Another disadvantage of the method is the need to increase the pH ofacid solution, discharged from the anode chamber, to a neutral value of5.5-7.5, because of the high pressure of anolyte, using catholyte tomeet this objective. Catholyte is dispensed, using the separator typeauxiliary equipment.

Technical restrictions to the construction of electrolysers used and lowproductivity can be highlighted as the main disadvantage of the methodsdescribed; this requires the use of auxiliary equipment for increasingthe efficiency and ensuring the circulation of concentrated electrolyte,for cooling electrolyte and bringing the pH value of used disinfectantsto the required neutral value of 5.5-7.5.

The patent RU2350692 provides a detailed description of diaphragmelectrolysers with cylindrical flow; this type is used for theimplementation of a majority of the methods, described above. Thelargest is capable of producing 25 grams of active chlorine per hour,therefore, the use of the aforementioned electrolysers for massproduction purposes is complicated, as more than 150 grams of activechlorine per hour is required there.

A two-chamber coaxial electrolyser with the productivity of up to 150grams of active chlorine is known from the patent applicationEE200700021, the main elements of the device being a tubular cathode, adiaphragm and an anode. The cathode is in an internal position, andbetween the cathode and the anode, the whole external electrode is ananode, which is coated from the outside with hydro and electricalinsulation of a red color. The anode, cathode and diaphragm are fitted,coaxially, with the upper and lower covers, which shall give the flow ofelectrolyte a spiral direction; branches of the anode chamber are madeinto the covers, having the dimensions, which will prevent the anodefrom being in an area, characterised by enhanced corroding properties,on the boundary of a liquid and gaseous stage. The disadvantage of thiselectrolyser is insufficient productivity—up to 150 grams of activechlorine per hour and the need to use external circulation, cooling andmixing equipment in efficient processes.

A cylindrical, membrane electrolyser (such as that described in pendingpatent application US2009266709) with an assembled anode and anassembled diaphragm is chosen as the prototype, having the followingmain elements: a tubular cathode (internal electrode), diaphragm, anode(external electrode), coated from the outside with a hydro and anelectrical insulation of red color, whereas both the diaphragm and theanode are assembled coaxially towards the longitudinal axis, usingsleeves with channels for the movement of electrolyte from one end ofthe anode to the other. Coaxial construction of the electrodes and thediaphragm is ensured with lower and upper covers, characterised by thedirection of the input and output channels, which give the movement ofelectrolytes along the electrodes a spiral nature. The upper cover hasan additional opening for exhausting cathode gases. The electrolyser iscapable of producing up to 600 grams of active chlorine per hour under along-term regime. However, the need to employ external circulation,cooling and mixing devices in efficient processes can be described asthe main disadvantage of this electrolyser.

BRIEF SUMMARY

The function of the disclosure is to produce disinfectants, using anelectrolyser and diaphragm electrolyse anodising products of a sodiumchloride solution with the pH value of 5.5-7.5, using 3-7 grams of saltper 1 gram of active chlorine, electrolysers with the productivity of upto 600 grams of active chlorine per device, a simplified hydraulicscheme—as compared to processes of comparable efficiency and involvingthe use of salt—and enhancing the reliability and safety of theequipment.

The above task will be accomplished by employing a method for obtainingdisinfectants, matching the patent application, involving theelectrolysis of sodium chloride solution into the anode chamber ofelectrolyser, whereby the following characteristic parameters must beensured: fresh water based electrolyte will be channelled into thecathode chamber, the quantity being equal to 0.4-0.8% of the quantity ofdisinfectant obtained, thus providing for high conductivity of thecathode chamber without an extra sodium chloride requirement. Thecatholyte will be eliminated from circulation immediately after beingdischarged from the electrolyser. Intensive conversion of sodiumchloride into active chlorine will be achieved not by creating highpressure in the anode chamber, but increasing the hold-up time ofelectrolyte in the anode chamber by cutting the flow through the chamberby 16-20% of the quantity of disinfectant acquired. The anolyte willacquire the concentration of active chlorine in the anode chamber, whichis safe for the materials used, and before being discharged from theelectrolyser, the concentration will be taken to a limit, which isrecommended for safe use of the disinfectant by the maintenance staff.High-productivity electrolyser is used, ensuring the cooling of smallquantities of electrolyte, and bringing the concentration of anolyte tothe level required of disinfectants.

The description of the suggested method is as follows: disinfectant isobtained from a sodium chloride solution with the concentration up to 12g/l, which flows through the anode chamber at the rate of 16-20% of thedisinfectant obtained; at the same time a solution, containing 0.2-12grams of sodium chloride per liter and 0.4-0.8% of the quantity ofdisinfectant, will be flowing through the cathode chamber; at the sametime, fresh water from a water supply network will be flowing through atubular cathode, directed towards the electrolyser's cover-mixer input.Anolyte, produced in the anode chamber, has active chlorineconcentration up to 3 grams. It will be raised to the branch in theanode chamber in the cover-mixer of electrolyser from the space adjacentto anode, where it is mixed with inflowing water and leaves theelectrolyser as a ready-to-use disinfectant with 5.5-7.5 pH level.Catholyte will be discharged into a utilisation device while hydrogen isdischarged into exhaust channels.

The diaphragm electrolyser has the following parts: an anode with acoaxial location, a diaphragm and a cathode (anode—external electrode;tubular cathode—internal electrode), and monolith covers with inputs forelectrolyte and outputs for electrolytic products. The upper cover hastwo outputs from the cathode chamber—one for catholyte and the other,higher up, for cathode gases. The electrolyser used is characterized bythe fact that the tubular cathode has hermetic caps at both ends. Thebottom cover of the cathode has a fresh water intake opening, while theupper cover has an output opening. Electrical terminals of the cathodeare welded to the cylindrical surface in the area between the bottomcover of the cathode and the bottom cover of electrolyser, while theupper cover of electrolyser has an opening for entering to the branch ofthe anode chamber at the same side with the disinfectant output opening.

The characterizing parameters of the proposed electrolyser are thefollowing: an internal tubular cooling cathode with covers and anopening for the inlet and outlet of fresh water, an upper cover-mixerwith an opening to let fresh water into the branch of the anode chamber.The productivity of electrolyser is 40-1200 liters of disinfectant atthe concentration of up to 500 mg active chlorine per 1 liter during thewhole production interval.

As the consequence of a joint implementation of the proposed method andcharacteristic features of the electrolyser, the disinfectant isobtained, under the method set out in the claims, by effective use ofsalt—3.0-7.0 grams of sodium chloride to produce 1 gram of activechlorine—as the same quantity of sodium chloride in electrolyte willrequire 5-6 times as much time to pass through the same anode chamber,being conserved as active chlorine more fully. The process is completelysafe for both the staff and environment, as the electrolyser is notoperating under pressure, while the product of electrolysis is ananolyte, which is obtained as the result of electro-chemical reactions,described with well-known formulas (Elektrochemische Kinetik, Dr KlausJ. Vetter, Springer-Verlag, 1961, §7), and the fluid has active chlorinecontent up to 3.0 g/l, which is safe for seals, materials and theelectrolysers as a whole, and involves active chlorine compounds, themain component being hypochlorous acid (HClO). Before leaving theelectrolyser, the concentration of anolyte will be brought to the levelcharacteristic of the concentration of disinfectant, which will be safefor the handling staff. A cooling cathode allows for excluding acatholyte circuit from the process. Exclusion of a circulation circuitshall enhance the reliability of the hydraulic scheme and allows forleaving out equipment used to create overpressure in the anode channel.Equal pressure in the electrode chambers will facilitate the emergenceof a neutral pH level of anolyte and allows for excluding a mixing placefor anolyte and catholyte from the process. The implementation ofelectrolysers developed shall give a chance to use the proposed methodfor achieving high productivity and lowering maintenance costs, as theuse of salt becomes more efficient, the construction of the system issimplified, while the reliability of the system is enhanced and thenumber of electrolysers, operating simultaneously at the consumer, willbe relatively smaller. Decreased mineralization of disinfectant willexpand the application of the agent.

The disclosure will contribute to considerable simplification of theprocess for obtaining disinfectants and lowering the related costs,expanding the production range while simplifying the maintenance ofproduction systems and expanding the possible areas of application ofthe ecological disinfectant thus obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a hydraulic scheme of an exemplary method and anelectrolyser for implementing the method;

FIG. 2 depicts a cooling cathode; and

FIG. 3 depicts a cover-mixer.

DETAILED DESCRIPTION

FIG. 1 shows that the hydraulic scheme of the exemplary methods involvesa number of flows. A fresh water flow 1 enters an inlet 21 at a bottomcover 22 of a cathode 20 and is then transferred though an internalspace of cathode 20, up to an upper cover 23 of the cathode 20, andthrough an outlet 24 as a flow 2, to an inlet 31 of a cover-mixer 30. Aflow 3 will be separated from flow 1 (or flow 2—not shown here) andenters a sodium chloride mixer 38, where a flow 4 is channelled as asodium chloride concentrate, which is then mixed and transferred, as theflow of anode chamber electrolytes 5, into an inlet 41 at a bottom coverof an electrolyser 40. The electrolyte will flow along a surface of ananode 50, through channels 61 in the body of a coupling sleeve 60,flowing as anolyte into the branch of anode chamber 32 in theelectrolyser's cover-mixer 30, mixing with flow 2, which is flowingtowards the channel 33 along the branch's perimeter, and shall exit as aflow 6 from an outlet 34 as a disinfectant at the consumer. Options areavailable for filling the cathode chamber through inlet 42 at the bottomcover 40 of the electrolyser; the suitable alternative is chosen,depending on technical feasibility. When choosing the electrolyte forthe cathode chamber: if fresh water is used as electrolyte, then thebranching should take place at 71 from flow 1 (or flow 2—not shownhere). If an anode chamber electrolyte is used as the cathode chamberelectrolyte, the branching should take place at 72 from flow 5.Electrolytes with special composition and purpose are transferred as anindependent flow 73. The flow of catholyte 8 will be discharged forutilization purposes from an outlet 35 of the mixer-cover 30. Hydrogenwill be emitted from an outlet 36 into an exhaust system.

FIG. 2 depicts a cathode 20, distinguished by being made as an open tube25. Tube 25 is fitted with hermetically sealed covers 22 and 23 withopenings 21 and 24, serving as water inlets and outlets. Tube 25 is alsofitted with electrical terminals 26, which are fitted to ensure theassembly of electrolyser 10 (see FIG. 1) to the area remaining betweenthe bottom cover 40 of the cylindrical outer surface of the cathode 20and the bottom cover of the cathode 22.

FIG. 3 depicts the cover-mixer 30, which has been shown, for thedemonstration purposes, assembled in part, with an anode 50 and adiaphragm 80. The cover-mixer 30 is fitted with a fresh water inlet 31,which is fitted with an outlet 34 at one facet of cover 38. Thedirection of the channel 37 of inlet 31 matches the spiral movementdirection of electrolyte inside the anode chamber. A guiding groove 33is devised to run along the full perimeter of the cylindrical branch ofthe anode chamber to facilitate mixing of water and anolyte. Thelongitudinal axis of groove 33 and centers of openings 31 and 34 are atthe same height.

The following examples are being used to illustrate alternatives forimplementing the proposed method.

Example 1

Example 1 gives the results of the method employed in Russian patentRU2297980, which have been achieved with an electrolyser disclosed inpending patent application US2009266709, having the geometricalparameters of the electrode chambers and the diaphragm, anode, cathodeand anode covering materials, which are identical to the electrolyser,developed within the framework of this intention, used in examples 2, 3,4 and 5. The results of example 1, obtained with the method employed inRussian patent RU2297980, are used to compare the results of otherexamples, as the utilized method is widely used, safe, and reproducible,as ready to use disinfectant and the catholyte is flowing out from theelectrolyser. Electrodes are inserted into anode and cathode chamberwithout any prior electro-chemical treatment and the method shall beoperable without any assistance from various auxiliary equipment, forexample, circulation circuits, additional electrolysers and pressureregulating devices in electrode chambers. The results of all theexamples are summarised in Table 1.

In example 1, used as comparison, the total flow of water used will bemixed with sodium chloride to achieve the concentration of 12 g/l andwill be then separated into two flows: one flow (520 liters per hour)will enter the cathode chamber while the other flow (620 liters perhour) will enter the anode chamber. The ratio of catholyte and anolytequantities will meet the interval, given by the method employed inRussian patent RU2297980—76.5%. Disinfectant is being produced, 680liters per hour (active chlorine content 850 mg/l, pH 2.4, reductionpotential (ORP) 1180 mV), using 24.8 g of sodium chloride per 1 g ofactive chlorine. The temperature of output solutions will exceed thetemperature of water originally used by 26° C. to 30° C.

Example 2

Example 2 gives the results for obtaining disinfectant under minimumflow conditions through the cathode and anode chamber, using exemplaryflow rate intervals specified by this disclosure. Fresh water ischannelled from an external course through channel 1 (the quantity being1,204 liters per hour (100%)) through the inlet 21 in the cover 22 ofcathode 20 to internal space in the cathode, cooling the cathode andalso the electrolyte in cathode chamber. After cooling the cathode, thefresh water will flow through channel 2, outlet 24 in the cover of 23 tothe inlet 31 of cover-mixer 30 in the branch of the anode chamber 32. Inthe area of channel 1 or 2 (not really relevant, depending on theconstruction of the device), before inlet 31, two flows are separatedfrom the fresh water flow: along channel 71 (channels 72 and 73 aremissing in this alternative) 4.8 liters of fresh water per hour (0.4%)to the inlet of the cathode chamber. Along channel 3 fresh water will beflowing at the rate of 200 liters per hour (16.6%) to the mixer ofsodium chloride 38 (the mixer shall be operating, using any recognisedmethod). The liquid shall then flow, as an electrolyte, with theconcentration of 10 g of sodium chloride per 1 liter, along channel 5 tothe inlet 41 of bottom cover 40 of the electrolyser 10. It shall flowalong anode 50, flowing as anolyte along the channels 61 in the body,the coupling sleeve 60 from one consecutive anode chamber to another,and will then be directed, as anolyte, having active chlorineconcentration of 3 g/l, to the cover-mixer 30 of the branch of anodechamber 32. Anolyte will acquire the required concentration on thecover-mixer 30 and will be then transferred as disinfectant toconsumers. The catholyte will then flow through channel 8 of outlet 35to a utilization facility. Hydrogen will be channelled to an exhaustthrough outlet 36. Disinfectant is produced at the rate of 1,200 litersper hour (active chlorine content 510 mg/l, pH 7.25, reduction potential(ORP) 890 mV), using 3.33 g of sodium chloride per 1 g of activechlorine. The temperature of output solutions will exceed thetemperature of water originally used by 6° C. to 17° C.

Example 3

In example 3 the disinfectant is obtained by allowing the fluids to flowalong the same route, which was specified in example 2, but at themaximum flow rates, set out in this disclosure, through the cathode andanode chambers, respectively, at 0.8% (that is, 10 liters per hour)through the cathode chamber and at 20.6% (that is, 280 liters per hour)through the anode chamber. Disinfectant is produced at the rate of 1,360liters per hour (active chlorine content 505 mg/l, pH 7.27, reductionpotential (ORP) 860 mV), using 6.9 g of sodium chloride per 1 g ofactive chlorine. The temperature of output solutions will exceed thetemperature of water originally used by 5° C. to 15° C.

Example 4

Example 4 sets out the results for an alternative configuration, whereelectrolyte arrives along channel 72 to inlet 42. The channel branchesoff from channel 5 (channels 71 and 73 are missing in this alternative).The quantity of electrolyte being 12 liters per hour (1%), the remainingfluids are flowing along the routes shown in Example 2. For anodetreatment, the quantity of arriving fluid is 240 liters per hour (20%),the concentration of both anode and cathode electrolyte being 11.7 g ofsodium chloride per 1 liter. Disinfectant is produced at the rate of1,200 liters per hour (active chlorine content 500 mg/l, pH 6.2,reduction potential (ORP) 920 mV) by using 4.9 g of sodium chloride per1 g of active chlorine. The temperature of output solutions will exceedthe temperature of water originally used by 7° C. to 18° C.

The working name of the disinfectant, produced under the method,involving the use of fresh water, as cathode chamber electrolyte, asdescribed in this disclosure, is, at the proposal of the authors,ANW—anolyte-neutral-water based; and when using the same solution as theelectrolyte of both anode and cathode chamber, ANS—anolyte-neutral-saltbased.

Example 5

Example 5 is given for further justification of the concentration rangeof cathode chamber electrolyte, developed for the purposes of thisdisclosure. In Example 5, electrolyte at the concentration of 300 g ofsodium chloride per 1 liter will be flowing along channel 73 (channels71 and 72 are missing in this alternative) to the cathode chamber; theremaining fluids are flowing along the routes shown in example 2.Disinfectant is produced at the rate of 1,228 liters per hour at theflow rate of 200 liters per hour through the anode chamber and 10.0liters per hour through the cathode chamber (active chlorine content 545mg/l, pH 3.4, reduction potential (ORP) 1160 mV), using 22.4 g of sodiumchloride per 1 g of active chlorine, the temperature of output solutionswill exceed the temperature of water originally used by 4° C. to 15° C.

The analysis of implementation results of the methods tells us thatincreasing the flow rate through the cathode and anode chamber of thesame electrolyser, also increasing the sodium chloride concentration inelectrolyte in cathode chamber will not impose any restrictions to theimplementation of the method. The analyses shows that optimumresults—for the purposes of effectiveness and availability—will beachieved under the flow rates through the cathode and anode chamber,accordingly to the disclosure, and electrolyte concentration rates,which are entered into cathode and anode chamber.

Useful side effects of the method is the decrease of power consumptionfor producing 1 g of active chlorine in all the examples, compared tothe method employed in Russian patent RU2297980, considering the lossthrough transformers and rectifiers to be approximately 2.1-2.4-fold.

TABLE 1 Examples No Parameter Unit 1 2 3 4 5 1 Quantity of l/hour 6801200 1357 1200 1228 disinfectant 2 Quantity of catolyte l/hour 520 4.810 12 10 3 Water consumption l/hour 1200 1205 1367 1212 1228 4 Flowthrough anode l/hour 680 200 280 240 200 chamber 5 NaCl in catolyte g/l12.0 — — 11.7 300 6 NaCl in anode g/l 12.0 10 16.9 11.7 61.0 chamber 7pH of the disinfectant unit 2.4 7.25 7.27 6.2 3.4 Reduction potential mV1180 890 860 920 1,160 (ORP) Active chlorine mg/l 850 510 505 500 545content 8 Total NaCl g/hour 14400 2000 4720 2952 15000 consumption 9Productivity by active g/hour 580 612 684 600 668 chlorine 10 NaClconsumption for g/g 24.8 3.33 6.9 4.92 22.4 active chlorine 11 Voltagein V 20.9 10.4 11.8 10.4 10.6 electrolyser 12 Current A 600 640 640 600600 13 Temperature of: ° C. 22.4 21.5 23.6 21.2 25.0 Original waterCatolyte ° C. 52.0 27.0 29.2 28.0 29.2 Disinfectant ° C. 48.0 38.0 39.239.0 38.6

The invention claimed is:
 1. A method for obtaining a disinfectant froman aqueous solution of sodium chloride by using a diaphragm electrolyserhaving a tubular cathode as an internal electrode, an anode as anexternal electrode, and a cover-mixer having a branch in communicationwith an anode chamber of the electrolyzer, the method comprising:providing a first fresh water flow and directing the first fresh waterflow to an internal space of the cathode; separating a second freshwater flow from the first fresh water flow and channeling the secondfresh water flow into a cathode chamber of the electrolyser, wherein theflow rate of the second fresh water flow through the cathode chamber is0.4-0.8% of the flow rate of the first fresh water flow through theinternal space of the cathode; separating a third fresh water flow fromthe first fresh water flow and channeling said third fresh water flow toa sodium chloride mixer to form a solution having sodium chlorideconcentration of 0.02-1.2% wt/vol; channeling said solution to the anodechamber of the electrolyzer as an anolyte flow, wherein the flow rate ofthe anolyte flow through the anode chamber is 16-20% of the flow rate ofthe first fresh water flow through the internal space of the cathode;channeling both the anolyte flow from the anode chamber and the firstfresh water flow from the internal space of the cathode to the branch ofthe cover-mixer in communication with the anode chamber; reducing aconcentration of active chlorine in the anolyte flow by mixing saidanolyte flow with the first fresh water supply in the branch of thecover-mixer in communication with the anode chamber to form adisinfectant having with a pH level of 5.5-7.5; discharging said secondfresh water flow from the cathode chamber for utilization; dischargingthe disinfectant from the electrolyzer; and channeling hydrogen from thecathode chamber at an exhaust outlet.
 2. A method for obtaining adisinfectant from an aqueous solution of sodium chloride by using adiaphragm electrolyser having a tubular cathode as an internalelectrode, an anode as an external electrode, and a cover-mixer having abranch in communication with an anode chamber of the electrolyser, themethod comprising: providing a first fresh water flow and directing thefirst fresh water flow to an internal space of the cathode; separating asecond fresh water flow from the first fresh water flow and channelingsaid second fresh water flow to a sodium chloride mixer to form asolution having sodium chloride concentration of 0.02-1.2% wt/vol;separating said solution into an anolyte flow and a catholyte;channeling said catholyte flow into a cathode chamber of theelectrolyser, wherein the flow rate of catholyte flow through thecathode chamber is 0.4-0.8% of the flow rate of the first fresh waterflow through the internal space of the cathode; channeling said anolyteflow to the anode chamber of the electrolyser, wherein the flow rate ofthe anolyte flow through the anode chamber is 16-20% of the flow rate ofthe first fresh water flow through the internal space of the cathode;channeling both the anolyte flow from the anode chamber and the firstfresh water flow from the internal space of the cathode to the branch ofthe cover-mixer in communication with the anode chamber; reducing aconcentration of active chlorine in the anolyte flow by mixing saidanolyte flow with the first fresh water supply in the branch of thecover-mixer in communication with the anode chamber to form adisinfectant having with a pH level of 5.5-7.5; discharging saidcatholyte flow from the cathode chamber for utilization; discharging thedisinfectant from the electrolyser; and channeling hydrogen from thecathode chamber at an exhaust outlet.
 3. A method for obtaining adisinfectant from an aqueous solution of sodium chloride by using adiaphragm electrolyser having a tubular cathode as an internalelectrode, an anode as an external electrode, and a cover-mixer having abranch in communication with an anode chamber of the electrolyser, themethod comprising: providing a first fresh water flow and directing thefirst fresh water flow to an internal space of the cathode; separating asecond fresh water flow from the first fresh water flow and channelingsaid second fresh water flow to a sodium chloride mixer to form asolution having sodium chloride concentration of 0.02-1.2% wt/vol;channeling said solution to the anode chamber of the electrolyser as ananolyte flow, wherein the flow rate of the anolyte flow through theanode chamber is 16-20% of the flow rate of the first fresh water flowthrough the internal space of the cathode; channeling both the anolyteflow from the anode chamber and the first fresh water flow from theinternal space of the cathode to the branch of the cover-mixer incommunication with the anode chamber; reducing a concentration of activechlorine in the anolyte flow by mixing said anolyte flow with the firstfresh water supply in the branch of the cover-mixer in communicationwith the anode chamber to form a disinfectant having with a pH level of5.5-7.5; channeling a catholyte flow into a cathode chamber of theelectrolyser by an independent channel, wherein said catholyte is asodium chloride solution and wherein the flow rate of catholyte flowthrough the cathode chamber is 0.4-0.8% of the flow rate of the firstfresh water flow through the internal space of the cathode; dischargingsaid catholyte flow from the cathode chamber for utilization;discharging the disinfectant from the electrolyser; and channelinghydrogen from the cathode chamber at an exhaust outlet.